Strophomenida

Leptaena is an extinct genus of mid-sized brachiopod that existed from the Dariwilian epoch to the Emsian epoch, though some specimens have been found in strata as late in age as the Tournasian epoch. Like some other Strophomenids, Lepteana were epifaunal, meaning they lived on top of the seafloor, not buried within it, and were suspension feeders.

thumb|240px|right|Strophomena costellata from Bromide Formation, Oklahoma, USA

Strophomenida is an extinct order of articulate brachiopods which lived from the lower Ordovician period to the mid Carboniferous period. Strophomenida is part of the extinct class Strophomenata, and was the largest known order of brachiopods, encompassing over 400 genera. Some of the largest and heaviest known brachiopod species belong to this class. Strophomenids were among the most diverse and abundant brachiopods during the Ordovician, but their diversity was strongly impacted at the Late Ordovician mass extinction. Survivors rediversified into new morphologies in the Silurian, only to be